Storage of liquid fuels



July 10, 1951 E. BERL 2,560,152 STORAGE 0F LIQUID FUELS Filed Aug. 6, 1946 2 Manamr/z 007: 57 of v wa/rd gusts low dense acf/vah'd Carbon Rawder or small aker;

BY WMA A TTORN E YE.

Patented July 10, 1951 UNITED STATES i ATENT OFFICE 2,560,152 STORAGE or LIQUID FUELS Ernst Bel-1, deceased, late of Pittsburgh, Pa., by Walter G. BerLxecutor, Pittsburgh, Pa.

Application August '6, 1946; Serial No. 688,681

rather high volatile materials igniteveryfeasily in case of accidents. They can be ignitdialSo bybullets. A container which "by any accident is hit or destroyed loses more or less of this liquid fuel which, intentionally or unintentionally, can beignited and burns with large and hot flames.

Several propositions "have been inadeto decrease the danger which is connected with this high volatility of liquid fuels. Most of these proposals, 'for instance their (complete solidification by the use of cold, are too complicated andtoo expensive so that actually no means are usedto decrease the danger which is connected with this high volatility of those liquid "fuels.

It is, therefore, an object of this invention to provide an internal combustion engine fuel which is explosion-proof even at higher temperatures or -under the impact'of a sudden shock.

Another object of the invention is a fuel having the above properties andat the same-time having little weight and takingup-little-space as compared with its calorificcontent.

Another object of the invention is the: provision of an aeroplane Jengine fuel which'will not explode in a crash or when its container is hit by an ordinary or incendiary projectile.

Still another object of the invention is the disclosure of such a safety fuel as is easy to produce, economical in storage, and convenient to feed to the engine.

Other objects of the invention will become readily apparent from the specification.

It has been found by the inventor that many of the d'ifliculties pointed out above can be avoided by absorbing the volatile liquidfuels on substances with highly developed internal surface and which possess a very low apparent density, such as silica gel or activated carbon. Certain qualities of activated carbon are especially suitable for these purposes. It is known that one can absorb liquid fuels by activated carbon. U. S. Patent 832,826 of C. G. Coleman uses for the filling of safety reservoirs for explosive fluids, for instance liquified acetylene,

The same inventor,

coal. 'that'these views are wrong. The'gas mask coal carbons.

The same inventor in-his U. S. Patent 1,080,26-3, page -1, line 78, uses some absorbent solid,

such as for example baked,- porou-s-likepipe clay. According to U. S. Patent 1,816,825 of A. E. Ray 9; solidified fuel can be made by usinga combustible, but not violently combustible, filler, for instance wood fiber, wood pulp, wood flour, etc, charcoal and carbon (page 2, line 33).

I A typical gas mash coal which is characterized by 'itshigh apparent density should; according to views prevailing until now, adsorb much more of volatile fuel than a typical decolorization The researchesof the inventor'have'proved adsorbs less liquid fuel than certain decolorizing I The very astonishing fact has been found'by'the inventor that the apparentdensity of active carbon is a most important factor.

' This apparent densityis characteristic for every kind of" activated carbon. Itcannot be -changed fundamentally by converting coarse -material in tea fine powder by intensivegrinding; Up to nowactivated carbons with low'apparent densities (.07-.20)' which, according to this invention, are especially suitable for the storage of voiatile liquid fuels have not been used for this purpose. This'density of activated carbons depends'upon the raw material which has been used, and depends to'a lesser extenton the chosen process of carbonization. Activated carbons with low apparent 1 density can be produced according to my U. S. Patents 1,851,888 and 1,812,316. My last-namedpatent, No. 1,812,316, particularly deals with an activated c arbon havingan'active surface of more than 700 sq; m.-/g. According to Table I-thelow 'app'arent'density is necessaryfor the right'efiect,

Table-I shows the fundamental difierence between different: activated carbons. Table II shows how manytimes morecarbonM (No. 1)

with the-lowestapparent density adsorbs benzene,

iso-octane, and alcohols than theother five carbon qualities. One part in weight of activated carbon M with the low apparent density of .071 takes up 9.25-10.92 times its weight of those different volatile fuels. Carbons with high apparent density (ATC 500 and W, .No. '5 'andl6) adsorb under the same conditions only 1.-40 2.0'5

' parts of weight of the same fuels. Thejtypical oocoanut shell coal C '(No. 4) under th'e'same conditions adsorbs 1.2 to 2.8 parts of those fuels. One can press out those combinations of. activated carbon and liquid fuel until. no, liquid fuel flows any more. Carbon M (No. 1).retains then 6.66-7.18 parts of fuel per one part in weight of carbon. Carbons ATC 500 and W (No. and 6) under the same conditions adsorb only 1.01-1.64 parts of fuel per one part (in weight) of carbon. Between carbon M (No. 1) and ATC 500 and W (No. 5 and 6) stays cocoanut shell carbon C. It adsorbs, in pressed state, 318-239 parts in weight of those liquid fuels.

Table II gives the relative figures which show how many more times carbon M (No. 1) with the lowest apparent density adsorbs different fuels than the other carbon qualities 2 to 5. For instance, it absorbs 2.87 times more benzene than the next best carbon A (No. 2) and 6 times more benzene than the carbon ATC (No. 5). Table III compares Carbon MB No. 710 with kapok.

It seems, therefore, that the capacity to take up larger amounts of liquid fuel and to retain this rather strongly is a function of the apparent density of the adsorbing activated carbon. Columns E, F, and G (Table 1) show that the apparent density (column B) multiplied by the weight of the adsorbed liquid (columns Ca, Cb,

D0,, Db, Ea, Eb) is fairly constant, especially for the carbons with lower apparent density. Carbons No. 5 and 6 show a rather strong deviation from this rule which means that the adsorbing capacity with increasing apparent density becomes much weaker.

Those activated carbons with low apparent .density have not been used until now to a large extent. In all those cases where as raw material for the production of activated carbon dense material like wood, cocoanut shells, peat, brown coal, or bituminous coal is used, activated carbons with rather high apparent densities (.2 to -65) result. The two-mentioned American Patents 1,851,888 and 1,812,316, especially the first-mentioned, allow the production of those very important carbons with low apparent density which posses this unexpected effect concerning the high and strong adsorption of these liquid fuels.

Activated carbons of low apparent density which are charged with volatile liquid fuels do not lose any liquid if the container is damaged. The liquid fuel adsorbed by these activated carbon does not ignite easily, and, if ignited, then the fuel burns very slowly so that there is no danger that through a quick burning of larger amounts of liquid fuels or through violent explosions persons may be hurt. Volatile liquid fuels which are adsorbed on this activated carbon with low apparent density will not be ignited if bullets with high speed perforate the container.

'The liquid volatile fuels are taken up by this activated carbon with low apparent density with rather strong development of heat. Carbon M (No. 1) and carbons A and B (No. 2 and 3) give practically the same heat of absorption. Nevertheless, carbon M is much superior to A and B due to its low apparent density.

Volatile liquid fuels adsorbed on activated carbon with low apparent density show a lower vapor pressure than the pure form. They get, so to speak, the quality of a high boiling fuel, for example Diesel oil.

moval of the liquid fuel from the adsorbents. The system: activated carbon with low apparent density plus adsorbed liquid fuel, has to be put in a suitable apparatus, for instance a tubular cooler. The activated carbon may be stored, for

4 example in the space between the tubes. Hot gases, for instance exhaust gases from the motor, have to be sent through the tubes in indirect heat exchange with the fuel. For starting, heat from an outside source may be used. At temperatures above the boiling temperature of the liquid fuel, this will be separated from the activated carbon. With the necessary air without or with a certain amount of water, or steam, the vapors of the now gaseous fuel enter the combustion cylinder where they burn after their ignition.

'When the adsorbed liquid fuel has been partly or completely eliminated from the active carbon, the necessary cooling before new liquid fuel can be added has to be performed. This can be carried out by sending cool air or cool water through those tubes where before hot gases are introduced. One can cool the heated activated carbon with cool air directly in those cases where practically all adsorbed liquid fuel has been removed. It has been found advantageous to put the activated carbon in rather thin layers between perforated sieves so that no mechanical losses result. When the active carbon has again reached lower temperatures, it can be charged with new amounts of liquid fuel whereby during this operation cool air or cool water has to be sent advantageously through the cooling tubes, this to remove the heat of adsorption. This process of charging and removing the liquid fuel can be carried out many times without changing the qualities of the adsorbing material.

After a great number of charging and discharging operations the adsorbents may be steamed with dry steam. During this steaming, if it is carried out in the same storage apparatus, hot gases may advantageously be introduced in the tubes of this tubular apparatus. During the former use high boiling fractions of these liquid fuels may have been accumulated and certain condensation reactions of fuel components under formation of larger molecules may have occurred. They decrease the adsorption capacity of the adsorbents. Steaming, heating from the outside, and carrying out this operation advantageously in vacuum removes those injurious substances practically completely.

In the drawings,

, Fig. 1 shows a longitudinal and Fig. 2 shows a transverse section through a fuel storage apparatus according to my invention.

The apparatus consists of a tank, inside of which is arranged a plurality of tubes substantially parallel to its longitudinal axis. Interstices between the tubes are filled with activated carbon of low apparent density, in powdered form, or in small pieces. The carbon is charged with liquid fuel in the above-described manner. In operation, the fuel is liberated in vapor form through an outlet connected directlyor indirectly with the engine by heating the system above the boiling point of the fuel. The heat may be furnished by exhaust gases introduced into the tubes at one end of the apparatus; they are discharged, somewhat cooled, into the atmosphere at the'other end of the apparatus. Inlets andoutlets for steam, air, hot gases and cooling gases are provided for direct communication with the fuel-adsorbing carbon, in order to control the operation of the apparatus at will. A manometer and other .control instruments may also be connected.

The use of low density activated carbon and the adsorption of liquid fuels in appropriate storage apparatus and its removal represent ,no difiiculties. The safety of aeroplanes .or-automobiles'or any other construction which uses these volatile materials is greatly improved by this invention.

This application is a substitute for my prior application Serial No. 304,720, filed November 16, 1939 and now forfeited.

Having now fully described the invention, without however limiting it to the examples disclosed in said description, and intending to limit the ent density not exceeding .2, an inlet to said tank for supplying a volatile liquid fuel to be adsorbed by said carbon, an outlet in said tank passing to an internal combustion engine for the passage of desorbed fuel vapors, and means connected to the exhaust manifold of said internal combustion engine for conducting exhaust gases through said tubes.

2. A fuel storage and liberating system accordscope'of the invention solely by the appended claims, ing to claim 1, wherein the apparent density of Table I A B 0 D E F G H Benzene Isa-octane Ethanol Apparent den- Apparent den- Apparent den- No sity'B multisity B multisity B multi- Apparplied by plied byplied by- Oarbon quality ent density wet pressed wet pressed wet pressed a b a b a 12 Ca Ob Da Db Ea Eb wet pressed wet pressed wet pressed 1 M, MB No. 710 .071 10. 92 7.18 9. 7.04 10. 9 6.66 773 510 .657 500 773 473 2 A, MB No. 800 144 5,03 4. 48 4. 80 4.40 4.48 3. 77 725 645 692 663 645 543 3 B, MB No. 700 .162 4. 92 4. 43 4. 50 4. 32 797 717 .676 700 4 Oocoanut shell carbon,

C, MB N o. 150 281 2.8 2. 39 2. 41 2.19 787 .670 .728 614 3. 37 2.19 6 ATO 500, MB No. 70 37 1. 82 1.30 l. 40 l. 01 665 48 52 372 6 W Wood charcoal MB MB N o. mg. methylene blue adsorbed by 1 gram of carbon. The figures under 0, D, E represent gram adsorbed material per 1 gram of dry carbon.

Table II 30 said activated adsorbent carbon is between .071

and .162. 8%3 17 Z= 8% 3. A method of storing and liberating a liquid 1m, fuel for use in an internal combustion engine, m' Tai 6177 E5T 55 comprising the steps of adsorbing a liquid fuel in activated carbon having an active interna1 surfif m 547 isT' F6? face of at least 700 square meters per gram and D an apparent density not exceeding .2, liberating 526" 5'35"? 5177 55 is? said adsorbed fuel and passing the resulting fuel Em vapors to an internal combustion engine by passfi E' 40 ing the hot exhaust gases from the internal com- E11, bustion engine in indirect heat exchange with the E 2B' fi 55 adsorbed fuel.

4. The method according to claim 3, wherein Table III the apparent density of said activated adsorbent carbon is between .071 and .162. A B C D 5. In the method, according to claim 3, the step of admitting a hot neutral gas to said adsorbed Isa-octane Ethanol fuel- Adsorbing Apparent 6. In the method, according to claim 3, the step material density wet pressed wet pressed of admitting steam to said adsorbed fuel.

a b a b WALTER G. BERL, No.1 MB No.710. .071 9.25 704 10.9 6.66 Executor of the Estate of Ernst Bert Deceased- No.7 Kapok 4.07 .505 4.47 .99

REFERENCES CITED ratios The following references are of record in the 5- J- and file of this patent:

.7 a .7. 1 12.1.71 2.27 E.1.b 6.7 UNITED STATES PATENTS E.7.a T and E777? Number Name Date 123,683 Dennis Feb. 13, 1872 What is claimed is: 887,989 Weber May 19, 1908 1. A fuel storage and liberating system for use 1,256,136 Plamk 1918 with an internal combustion engine, comprising 1,661,149 Barnebey Feb. 28, 1928 a tank, a plurality of parallel tubes traversing ,312,3 6 Berl --J11ne30, 9 1 said tank, an activated adsorbent carbon tored 1,851,888 Berl Mar. 29, 1932 in said tank between said tubes, said activated 2,083,732 Moore et a1 e 1 1937 carbon having an active interna1 surface of at 2,234,734 Maude Mar. 11,1941 least 700 square meters per gram and an appar- 

